An unpopular model of the Colt M16/AR/M4 family. It was adopted by the US during Vietnam as an aircraft crew rifle. It's brother the XM608 was also used for this but failed.
It used a spring stock system that would propel the stock out (it was spring loaded)to another position. It also had the looks of a fixed stock,just shorter.It also had the trianguler M16A1 grips. Of course they were shorted though. It also had a long flash hider. Time to tell you how it failed.Well at the time,sub machine guns were hard to make. They had alot of recoil. As you can geuss,this one did too. the XM607 also in addtion to recoil had a large muzzle flash. This gave away the soldiers postion.
The XM607 got a new name in a way in the year of 2003 suprisingly from the sport airsoft. The brand Tokyo Marui made a XM607 with the name CAR 15. The CAR 15 is actually the Colt M733 Comando. The improvement of the X607.

When you eat dirt for the first time and leave your family to build a shack in the woods